1. Field of the Invention
This invention concerns a dispensing device for at least one liquid, or a more or less thick pasty product, that makes it possible to dispense cosmetic or pharmaceutical products.
2. Description of the Related Art
It is known for dispensers to consist of a container holding the product to be dispensed and a dispensing head attached to the container and incorporating a channel that connects the container to an external dispensing orifice.
From EP-A 0 410 857, FR-A 2 660 877, FR-A 2 666 308 and the French patent application 91 06 097, it is known for this external dispensing orifice to be closed by a closure system comprising two elements: a stopper and a seating, at least one of these two elements being elastic. The two elements are in contact when no dispensing is taking place but move apart by elastic deformation of at least one of them under the pressure of the product being dispensed. The stopper may consist either of a lip that moves away from its seating by bending parallel to the direction in which the product is emerging, or of a membrane with a slot placed under constraint, or of a wedge on top of a flexible dome. The stopper is preferably made of an elastic material and is subjected to the action of a constraining body that tends to keep it pressed against the seating to which it conforms. The seating may also be elastic, but is more usually rigid.
The stopper-seating closure system may involve a dispensing head that is entirely fixed, the head being attached to a deformable container activated by the user, in which case the dispensing channel will consist of a rectilinear passage or may have various segments at an angle to one another. The dispensing head may comprise a pumping system that can be actuated by the user, and a second valve. In one version, the dispensing head with a pumping system may comprise, on the one hand, a fixed dispensing part attached to the container, which comprises a second valve able to close off the communication between the container and the dispensing channel, and on the other hand, a moving portion forming a pumping system activated by the user: the dispensing channel is then located between two valves, one attached to the container and the other attached to the moving portion of the dispensing head. In this version the dispensing channel comprises a pumping chamber that can be sealed off by the second valve, and a passage that connects the pumping chamber to the outside. In this version of the dispensing head the moving portion may be removable from the fixed part. In a different version, the dispensing head comprises a deformable part located opposite a chamber that the user presses to pump the product; in this case, the dispensing channel includes the pumping chamber and is also located between two valves. Various types of known dispensers to which the present invention can be applied, are illustrated in FIGS. 1 to 8 attached.
The stopper-seating closure system allows almost no ingress of air through itself. Consequently, the product remaining in the dispensing channel has practically no contact with air after being dispensed. This avoids much of the risk that the dispensed product might become degraded by contact with the air, either by oxidation or by microorganisms. It has been found, however, That the dispensed product may still become slightly degraded by oxidation or microorganisms, and that it may consequently lose some of its qualities.